1.63-billion-year-old multicellular eukaryotes from the Chuanlinggou Formation in North China

Multicellularity is key to the functional and ecological success of the Eukarya, underpinning much of their modern diversity in both terrestrial and marine ecosystems. Despite the widespread occurrence of simple multicellular organisms among eukaryotes, when this innovation arose remains an open question. Here, we report cellularly preserved multicellular microfossils (Qingshania magnifica) from the ~1635-million-year-old Chuanlinggou Formation, North China. The fossils consist of large uniseriate, unbranched filaments with cell diameters up to 190 micrometers; spheroidal structures, possibly spores, occur within some cells. In combination with spectroscopic characteristics, the large size and morphological complexity of these fossils support their interpretation as eukaryotes, likely photosynthetic, based on comparisons with extant organisms. The occurrence of multicellular eukaryotes in Paleoproterozoic rocks not much younger than those containing the oldest unambiguous evidence of eukaryotes as a whole supports the hypothesis that simple multicellularity arose early in eukaryotic history, as much as a billion years before complex multicellular organisms diversified in the oceans.

Raman spectrum showing fitted bands (sub-peaks).Spectrum was baselined corrected and decomposed following the peak fitting procedure in (34).

Fig. S5. Floating bar chart showing cell width range of extant uniseriate filamentous
prokaryotes belonging to 11 bacterial and 1 archaeal phyla.Taxa producing endospore are marked with a red asterisk.Source data are provided in table S4 and cited references in table S5.Abbreviations of taxa are provided in the legend of (A).Measurements of Q. magnifica are provided in Source Data 1.Size data of Eosolena loculosa (9), Eosolena minuta (12), Rafatazmia chitrakootensis (14), Segmentothallus asperus (78) and Devonian algae (25) were measured from scaled illustrations in the literature or directly cited from the literature and provided in Source Data 3.

Fig. S1 .
Fig. S1.Stratigraphy and geological map of the study area.(A) Generalized stratigraphic column showing Proterozoic strata in the Yanshan Range with age constraints and fossil horizon.Lithology is based on stratotype sections in Jizhou area from ref. (80).Radiometric dates are from refs.(23, 81-87).(B) Location map of the North China Craton (NCC).(C) A simplified geological map showing Proterozoic outcrops in study area (red box in B) with fossil locality.

Fig. S3 .
Fig. S3.Micrographs of Qingshania magnifica from the Chuanlinggou Formation.(A) TL photomicrograph of a filament with transverse rings (tr).(B) SEM image of (A).(C, D) Magnifications of (B), showing smooth wall surface and the well-defined contact between adjoining cells as indicated by a very shallow groove (marked by cyan arrowheads) along the transverse ring.(C) represents the dashed box in (A) and (B); (D) corresponds the dashed box in (C).tr: transverse ring (interpreted as partially preserved cross wall).Scale bars equal 50 μm for (A, B), 10 μm for (C), and 2 μm for (D).

Fig. S6 .
Fig. S6.Morphometric analyses of Qingshania magnifica and similar fossil taxa.(A, B) Scatter plots of cell length and cell width of filaments.(B) Magnification of the dashed box in (A).(C) Grouped floating bar chart showing ratios of cell width to minimum cell width (CW/CWmin) and cell length to minimum cell length (CL/CLmin) within single filaments.Abbreviations of taxa are provided in the legend of (A).Measurements of Q. magnifica are provided in Source Data 1.Size data of Eosolena loculosa (9), Eosolena minuta (12), Rafatazmia chitrakootensis (14), Segmentothallus asperus (78) and Devonian algae (25) were measured from scaled illustrations in the literature or directly cited from the literature and provided in Source Data 3.